newb wants advice on Revel SUB-15 clone

Discussion in 'Home Theater Projects' started by DanielGM, Nov 20, 2003.

  1. DanielGM

    DanielGM Stunt Coordinator

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    hey guys,
    I'd like to think I know a good deal about audio, but this will be my first DIY attempt, unless you count a pair of flexy speaker stands and a flexy component rack [​IMG]

    I was originally thinking of going with building my own enclosure to mimic the Stryke Power 15.6 (2 15" drivers, 6 15" PR's) But for cost and simplicity I think I am going to try and build something like a Revel Sub-15 using a stryke AV15. Possibly not the best first choice for DIY, but personally I would rather not waste my time building a boring black box, and if it takes me till next summer to finish it then so be it, as long as I am happy with the performance and aesthetics. I am sure this thread will encorporate more questions later but for now the ones I am starting off with:

    1) I am using winISD to graph the output and I am getting a -3dB point of around 35 hz? (is this the f3, btw?)
    can someone comment on whether I am doing this right? You can find the box dimensions on page 36 of the owner's manual: http://revelspeakers.com/PDF_manuals/sub15le1_om_r1.pdf
    I am using stryke AV15 MK2 para. that I converted and entered myself, so they may be incorrect. If someone has a program with the correct T/S paras. and could graph a closed angled box with 7200 in^3 volume and verify my results that would be great.

    2)Am I going to be happy building this sub? I will certainly drive it to it's power handling capacity of 500 watts (that's for BOTH VC's, yes?)

    3)from the owner's manual schematic, I am slightly confused as to what the schematic is describing that is right behind the driver, the larger rectangle is blank, and the two smaller rectangles on top and bottom are hashed out, what does this mean exactly? and slightly further to the right there's one solid line, and then in the very center a smaller horizontal rectangle that's blank. Again, the meaning of this?

    Thanks for your help. Any comments you may have on this project that you would care to share would certainly help me out

    Regards,
    Daniel
     
  2. Stephen Hopkins

    Stephen Hopkins HW Reviewer
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    As far as subs go, the one you're looking at isn't very large in comparrison to many (probably most using 15" drivers) DIY subs. A small sealed sub by it's self isn't going to give you deep deep bass. The Revel you're looking at cloning i'm sure uses some sort of built in equalization or Linkwitz Transform to boost the lower frequencies. This gives you lower response in a smaller sealed sub but really eats into your power headroom. A much easier way to obtain low low bass is to port or passivly radiate the box. Cloning comercial subs in design usually isn't a great idea since they usually design their drivers and amps to accomodate a single certain physical constraint, where DIYers usually design their box around the driver. You can try to keep with the asthetics of the Revel but the only way you're going to get the kind of extension you seem to be looking for is an LT or ports/passive-radiators. It's not going to be possible to get 20hz extension w/ an AV15 in that size box even when ported, although you'll probably come close with room gain. You would have to go upwards of 7 ft^3 to get 20hz extension w/ a ported/pr box. Adding 15hz of extension to a 4.2 ft^3 box using an LT is going to requirer alot of power headroom.

    Also, if you ever fed an actual 500 watts to an AV15 (at 1m) you would be generating an SPL of 119db (probably more accounting for room gain). Bass beaks at refference level are around 110db. 9db over would be 8 times the power needed to reach refference level and would definitely damage your hearing if listened to for any extended period of time. Alot of power is great, but don't think you need to push a sub to it's limits to get great sound, or even loud sound.
     
  3. DanielGM

    DanielGM Stunt Coordinator

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    Stephen,
    Thanks for your reply. I just wanted to make sure I was doing things right. I thought there might have been some equalization, as they sell the SUB-15 with it's own external amp with some sort of processing ability, but I didn't read anything about about boosting the lower freq. Also, they are using a much better driver I am sure. Passive equalization is an option, but I think what I will end up doing is exaggerating the dimensions while keeping the same shape and then porting the box in the back, shouldn't affect the look much. I found I can get an f3 right at 20 hz if I increase the volume to around 10,000 in3 (5.7 ft3) and port the enclosure. Does this sound like a reasonable plan? Also, can anyone recommend a good source for LT info or a unit that would suit my purpose? What's vent match mean exactly?
     
  4. Stephen Hopkins

    Stephen Hopkins HW Reviewer
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    Sounds like you're on the right track. The thing about LTs is they have to be custom made for each driver and enclosure. There are some programs and excel worksheets out there to give you values for the electronic components and schematics. They're not too dificult to build but you do need alot of power. What amp are you planning on using?
     
  5. DanielGM

    DanielGM Stunt Coordinator

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    Probably a QSC offering that can bridge to 4 ohms (I know there are many) I havent quite decided. Used amps aren't terribly expensive.

    I understand that LT's are only for closed systems, so if I was talking about the original 7200 in3 box with the 35 hz f3, how much amp power will I need to get decent freq. extension and still hit reasonable (or rather, unreasonable) SPLs?

    What are my equalization options for boosting the response below 35 hz for the enlarged vented box? (it has an f3 around 20 on it's own, but a little added boost may be worthwhile if its not gonna cost me much. Besides, simple electronics projects can be fun)
     
  6. Stephen Hopkins

    Stephen Hopkins HW Reviewer
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    Equalization doesn't do a whole lot in terms of boost. That said, an equalizer would most likely make your sub sound alot better not by boosting lower frequencies but by helping tame peeks in your room response. The vented box shouldn't need any boost but depending on room and placement any sub can develop nasty peaks and nulls along the response curve. There's not alot you can do about the nulls but the peaks can be tamed significantly. The Berringer Feedback Destroyer is a favorite parametric eq on the HTF and is only about $130 new or less than $100 used if you can catch someone selling.

    I'm not terribly experienced with LT design and power requirements in specifics, but keep in mind that a 3db boost requires twice the power. Based on that and the F6, boosting the F3 to around 27db would cut your original power in half. Boosting the F3 to 22hz would cut your power by a factor of four, and 18hz by a factor of eight. So in essence, a 7220 in^3 sealed AV15 w/ an LT and an F3 of 18hz would effectivly turn a 800w amp into a 100w amp... 22hz would turn it into a 200w amp... 27 would turn it into a 400w amp. There's also limits to how much you can boost w/ an LT but I can't remember right off what they are or why they're there. It may have something to do with exceeding x-max at lower frequencies, but i'm not sure.
     
  7. DanielGM

    DanielGM Stunt Coordinator

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    steve,
    thanks for all your help this evening. I have some exp. with para. equalizers (I own infinity IL60's and an infinity IL120S with a RABOS kit)

    I'm gonna do some research over the weekend and see what my price/performance ratio is going to amount to ( I also need to buy tools for this project, but I'm thinking I can probably limit it to just a router and have home depot make all my cuts)

    I think my final design is going to amount to an 8000 in3 ported box (with blue metallic paint and brushed aluminum accents of course [​IMG], damn that sub is so sexy)

    I'm sure to have more questions in the upcoming few days, but again, thanks for you all your help so far
     
  8. Stephen Hopkins

    Stephen Hopkins HW Reviewer
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    For a first time DIY sub simple sealed or ported is really the way to go. The finish of a DIY sub is the best thing because you can do whatever you want and in the end even if it doesn't turn out exactly how you want it, it'll still sound great.

    If your Home Depot is anything like mine you'll want to do the cuts yourself. NOTHING i've ever had them cut has been square. I usually only have them cut stuff down small enough to fit in the bed of my truck. You may want to consider tool rental from Home Depot or cheap tools from Northern or Harbour Freight if two or three projects is all they'll see use for. If you think you'll be using the tools for other projects on down the road some decent home-owner grade tools would probably be a good idea. Craftsman, Black & Decker, or Ryobi all make solid home-owner grade stuff. For something more on the line of industrial grade (but also more expensive and probably not neccessary if you're not using them alot) would be DeWalt, Porter Cable, Nikita, and Milwaulky. I'm a Craftsman man myself, but coming from a father who owned a Sears Catalog store for 14 years while i was growing up and my first real job being at a Sears dealer store probably influences that (as well as alot of the great deals we were able to get along the way).

    In a worst case scenario the router along w/ a fence can be used to make all your cuts if you're patient and careful. I wouldn't reccomend it but it can be done. May be a little hard on bits and slow the process down quite a bit, but worst case it can be done.

    Good luck and have fun [​IMG]
     
  9. DanielGM

    DanielGM Stunt Coordinator

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    Did some research at home depot today and now I have more questions.

    first of all, I realize that home depot is not the place to get the cuts for my project, which is annoying, but oh well.

    So I saw this tool, and I think I want it, I just want to know if it's going to be good for my needs. The version I saw had two differences, Instead of a jig saw it was a circular saw. The circlular saw only cuts to 1" thickness, which may or may not be a problem depending on your answer the my question below
    The tool I saw didnt have a sander, it had a router instead, and I needed a new drill already, so this tool seems perfect for me. I could buy the cheapest router, circular or jig saw, and drill I can find, but I would still end up around 200, and this is going for 80. So, sound good?

    My second question is, HD only carries MDF up to 3/4" thick. Is this going to suit my needs? Originally I was going to go for an inch and a half and really overbuild this thing, but 1) I have no idea where to get that, and its probably expensive and 2) that power tool I want up there can't cut 1.5" thick board. So, will 3/4" with bracing be worth using, or is the thicker board really that much better? Would it be a good idea to cut identical 3/4" boards and glue them together for each side?

    final question of the post: I checked out clamps and they were asking like 40 bucks for one 36" clamp.. Is there any alternative to store bought clamps (I have a bunch of threaded rod from flexy projects that I could probably jerry-rig) How many clamps am I going to need?


    thanks for your input
     
  10. ThomasW

    ThomasW Cinematographer

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    Unfortunately 12 volt tools don't have a lot of 'grunt'. I suggest at least 14-18v.

    Cordless circular saws are a joke when it comes to cutting MDF. I have a 18volt DeWalt and it's best when used for softwoods like pine.

    Multi tools have one BIG problem. That is the mechanism that connects the various heads together wears out or breaks, then you've lost not one tool but three.

    A good cordless drill IMO is a must have, get one that is 14-18v. The other tools should be corded......

    Most DIYers buy 3/4" and laminate it up to the desired thickness.

    The low buck alternative for clamps is of course Harbor Freight Tools. Buy a ton of them.

    All-thread is a royal pain to use for clamping
     
  11. Dan Hine

    Dan Hine Screenwriter

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    I bought the 18v Milkwaukee set at Lowes about a year ago and I will never regret it. All the tools have worked great. And I've been able to make quite a few cuts on both 3/4" mdf and plywood with no problems using the cordless circular saw.a corded would be optimal but given the value of the set I got I can't complain.

    I do agree with Thomas on the downfall of "multi-tools." That's also a reason to never buy a dvd/vhs combo player. [​IMG]
     
  12. Stephen Hopkins

    Stephen Hopkins HW Reviewer
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    My 19.2 Craftsman cordless circular trim-saw has cut 3/4" MDF in the past but I too would suggest a corded circular because the MDF might eat into the longevity of the trim-saw. A great place to get corded tools are pawn shops. Older tools by good brands are bult like tanks. They may look a little used, but probably because they are. I got a DeWalt corded circular saw for $10 at a pawn shop a few months ago (cleaned it up and sold it for $75 on ebay).

    Multitools usually do multiple things acceptable but nothing well. The B&D tool you linked to would porbably do ok as a drill and as a detail sander, but the jig-saw most likely won't cut anything thicker than 1/4" plywood.

    A decent corded router, circular saw, palm sander, and cordless drill could all be had NEW from Sears (Craftsman) for under $200. If you paid $100 for that B&D multi tool and then add a circular saw and router you would be well over that mark. Even if you didn't need the router and the multi-tool jigsaw could cut the MDF (which is doubtful) a router w/ a circle guide would do a much better job. A jigsaw would work, but much easier and cleaner cut w/ a router. Also if you catch some sales (w/ Christmas comming up) you could pick up a 18v or 19.2v Drill/Saw/Light combo for around $150 or even less if they have a previous model on closeout (the Craftsman 75th aniversary 19.2 Drill/Saw/Light set hit $110 on it's final closeout price reduction). If you get just the drill, the 12v EX can really hold it's own and at $60 w/ a free cooler it's a solid buy.
     
  13. DanielGM

    DanielGM Stunt Coordinator

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    thank you for all the helpful replies. Unfortunately it seems the consensus is, 'spend more money' [​IMG] You are all making valid points, however, and so I will probably step up and buy some real tools, but besides the drill I don't know what I would use the other stuff for again other than speaker building.

    I'm going to take a look at some of the pawn shop's around here and see what I can find. It would be nice if there was someone in the area I could borrow tools from. I am trying to think of all the friends and uncles I have but none of them really have a decent set of tools that I know of.

    Is there any other option you guys can think of? Home depot won't do precision cuts, and definitely won't router. I am sure I could find some cabinet making shop or other outfit, but that would probably end up costing almost as much as just buying all the tools myself.

    So 3/4" mdf with bracing is going to be sturdy enough to meet my needs? When you say laminate im not sure what you mean, my impression of laminates is that they were never more than a quarter of an inch thick.

    once again thanks for all your help, I will do some more research tomorrow and see what I come up with
     
  14. ThomasW

    ThomasW Cinematographer

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    To 'laminate' (verb) means to glue more than one piece of material to another. This means gluing one piece of 3/4" MDF to another to create a single piece of MDF 1.5" thick.

    A 'laminate' (noun) is a thin material.

    If you really want to copy the Revel design you need a thick cabinet

    You really don't need a router. If one is careful, speaker cutouts can be done with a jig saw.

    You will need either a circular saw with a cutting jig or a table saw to get accurate cuts.
     
  15. DanielGM

    DanielGM Stunt Coordinator

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    Thanks for the laminate description. So the idea is to build the box then glue more panels on (as opposed to glue together then assemble)?

    Is there a way to finish the edges in that nice rounded off fashion without a router?(i'm talking about the cabinet part, not the aluminum part, I plan to find someone to help me make the alum. parts)
     
  16. John E Janowitz

    John E Janowitz Second Unit

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    Hi Daniel,

    A few things I figured I'd mention here. First I wrote something up a long time ago about tools for getting into speaker building. I started out with basically nothing but a jigsaw. Here's the little writeup I did:

    http://forum.stryke.com/viewtopic.php?t=2

    Regarding the Revel clone, a few things to mention. The driver they use is very close to our HE15 woofer. More Xmax, quite a bit more suspension travel, but also smaller cone area. The Revel is a very good sub, but you can get much more output than the Revel without much trouble. It is still limited by it's box size and the displacement of a single 15" driver. An AV15 in a box about like you said, 5.7cf with a proper vent or PR's will easily get you 6-10dB more output on the low end than the Revel. You will also be flat to well under 20hz without the need for EQ. With a pair of the 18" 1600gram PR's or 6"x30" long vent, you get an F3 point around 18hz.

    John
     

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